(Program
{(Comparison
  {-(Identifier)-}
  {-(Identifier)-})
->(Equal
  {+(Identifier)+}
  {+(Identifier)+}) }
{+(Not
  {+(Equal
    {+(Identifier)+}
    {+(Identifier)+})+})+}
{+(Equal
  {+(Identifier)+}
  {+(Identifier)+})+}
{-(Matches
  {-(Identifier)-}
  {-(Identifier)-})-}
{-(Assignment
  {-(Identifier)-}
  {-(Not{-(Identifier)-})-})- })